Various known apparatus exist for monitoring the condition or loading of lifting equipment. Such apparatus call for the use of certain physical or mechanical parameters such as the angle and the length of the jib or boom and the actual load while other more complex apparatus measure the load applied at the lifting attachment. Attendant data acquisition and handling enable compliance with the safety factor of the crane or other lifting equipment taken as a whole, (e.g. mechanical strength, overturning couple), but do not function with regard to the maximum permissible load on the load-lifting rope. One must clearly distinguish, however, between the rated load of the crane or other lifting equipment and that of the load-lifting rope which have entirely different values.
In association with certain systems there are manual switches which simulate the reeving as a function of the permissible load on the lifting attachment and the mechanical properties, namely strength, of the load-lifting rope. Still, such an arrangement obviously does not afford positive protection.